Thesis (Ph.D)-Cairo University, 2025.

Bibliography: pages 146-181.

This study aimed to isolate and identify the microbes associated with the
strawberry leaf blight disease symptoms. Samples of infected strawberry leaves
were collected from three governorates: Ismailia, Beheira and Kalubia. The
isolation process was carried out from naturally infected samples according to
standard bacteriological methods. Twelve bacterial isolates were obtained as
follows: four isolates from each governorate. The isolate IPa2 from Ismailia and
the isolate BPa6 from Beheira were the most aggressive isolates causing the
disease symptoms on healthy strawberry leaves. Therefore, according to the
cultural, physiological, biochemical characteristics the isolates IPa2 and BPa6
were selected to identify using 16S rRNA sequencing the two selected isolates
were identified as Pantoea ananatis with similatriy level of 97.05% with
accession number (MH_127816.1) for IPa2, as well as was the isolate BPa6
with similatriy of 97.05% with accession number (NR_026045.1). The 16S
rDNA sequencing were depositied in the Gen bank nucleotide data bases under
accession number (MH_127816.1) &(NR_026045.1), respectively. In vitro
experiments, three bacterial culture filtrates of B. subtilis and Ps. fluorescens ;
three essential oils; seven plant extracts and some safe chemicals were
suppressive to the growth of P. ananatis. The highest inhibition zones of 1.637,
2.158, 1.169,1.694cm were resulted form Ps. fluorescens, thyme, garlic extract
and salicalic acid, respectively. In field experiments, all the applied treatments,
either as root dipping or foliar spraying, significantly reduced the strawberry
leaf blight severity. The bacterial culture filtrates of B. subtilis was the most
effective treatment that decreased the disease severity to 19.0 and 14.0%. In
general, foliar spray application of the tested treatments were more effectval
than root dipping application. The application of all the tested treatments,
enhanced the estimated plant growth and yield parameters as well as the
activities of peroxidase, polyphenole oxidase and β-1,3 glucanase enzymes and
fruits quality parameters compared to the infected control.

هدفت هذه الدراسة إلى عزل وتعريف مسبب مرض لفحة أوراق الفراولة. جمعت العينات المصابة من ثلاث محافظات الإسماعيلية والبحيرة والقليوبية و إجراء عملية العزل وفقاً للطرق البكتريولوجية القياسية. حصلنا على اثنتي عشرة عزلة بكتيرية: أربعه من الإسماعيلية، أربعه من البحيرة، أربعه من القليوبية. كانت العزلتين Pa2 و Pa6 الاقوي من حيث شدة حدوث الأعراض على أوراق الفراولة السليمة. لذلك تم اختيارهما للتعريف باستخدام 16 SrRNA على أنهم P. ananatis بنسبة تشابه 97.05٪ برقم دولي (MH_127816.1) للعزلة Pa2 و العزلة Pa6 بنسبة تشابه 97.05٪ برقم دولي (NR_026045.1). بالمعمل، كان راشح مزارع بكتيريا B. subtilis و Ps. fluorescens اعلي تثبيطا ضد بكتيرياananatis .P لكن المستخلصات النباتية كانت الاقل. بالحقل أدت المعاملات لتقليل الاصابه بالمرض وحسنت النمو الخضري والمحصولي وجودة الثمار و زيادة النشاط الإنزيمي بالنباتات

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Text in English and abstract in Arabic & English.